1. Field of the Invention
The invention relates to an antistatic agent and an antistatic resin composition. More particularly, the invention relates to an antistatic agent which does not impair the mechanical property or good appearance of a molded article formed by molding a thermoplastic resin composition and which provides the molded article with an excellent permanent antistatic property even when added in a small amount, and an antistatic resin composition containing the antistatic agent.
2. Description of Related Art
Conventionally, as a method of imparting an antistatic property to a highly insulative thermoplastic resin, a method of kneading a small amount of surfactant into the thermoplastic resin is common. However, in a case that the antistatic property of the molded article formed by a resin composition is obtained through the addition of surfactant, an effect emerges by a low molecular weight surfactant bleeding out on a surface of the molded article. Accordingly, the antistatic effect of the molded article would be lost due to water washing, wiping and the like, and it was difficult to maintain a permanent antistatic property.
As other methods of imparting a permanent antistatic property to the thermoplastic resin, (1) a method of kneading an electrically conductive filler such as carbon black thereinto, and (2) a method of kneading a high molecular antistatic agent thereinto, and the like are known. Nevertheless, in the method (1), a large amount of electrically conductive filler is generally required to develop the antistatic effect; furthermore, there were problems that an obtained resin composition fails to achieve good workability and that a molded article formed by the resin composition is inferior in mechanical strength such as impact resistance.
In addition, the method (2) is known as a method of kneading a relatively smaller amount of high molecular antistatic agent such as polyetheresteramide (see Patent literature 1, for example) and polyether/polyolefin block polymer (see Patent literature 2, for example) into the resin. Nevertheless, in the method of kneading a high molecular antistatic agent into the resin, it is necessary to add more than 10 wt % of the high molecular antistatic agent to provide the thermoplastic resin with a sufficient antistatic property, and there was a problem of physical properties such as mechanical strength, thermal resistance, etc. of the molded article being lowered. Furthermore, from an economic point of view, it is preferred that the antistatic agent be able to impart a permanent antistatic property in an amount less than that conventionally.